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I would like to acknowledge Mr. Robert Britzke from Eureka Springs, Arkansas for pointing out the presence of Didymosphenia geminata in the tail race area of Beaver. Numerous collections were made from a variety of sites in March 2003 followed by March- May 2006. Many of the images in this talk were made at those sites and from the collected material.

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The brown color is due to fucoxanthin, a pigment contained in each cell, (although each cell also contains chlorophyll) and the white or translucent color is due to the stalks.

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What is Didymo? Where is it currently found? What are its positive effects? What are its negative effects? What can be done to control Didymo? Open discussion

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Didymo is a colonial diatom. Major characters are Silicon wall with precise ornamentation Oil and carbohydrate for storage product Each cell exudes extracellular polymeric substance, EPS,the material of stalks and resistant to degradation. There are phosphatases at the base of each cell where new stalk material is extruded. Phosphatases remove PO 4 from organic phosphate molecules. When cells divide, the stalks are formed anew but connected to the old stalk. Thus the stalk material continues to build up.

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Below are both a cell and stalk of Didymo found in the gut content of Gammarus which was living in the stalk portion of Didymo at the time of collection. Didymo is not known to produce any toxins and the oxygen content within the stalk matrix has been found to be supersaturated. A Gammarus found in a colony of Didymo

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Microscopic colony of Didymo scraped from a rock in the Beaver tailrace, March 2006 The ability of Didymo to remain attached to the substrate by the basal portion of the stalks probably contributes to its continued presence and redevelopment after a flood type event and/or seasonal changes. (1)

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Gomphonenma with stalks and division similar to Didymo. The major difference is that the stalk material of Gomphonema is slippery and that of Didymo is cottony.

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A site downstream from the tailrace region of Beaver as well as other locations in the tailrace region. Russ Rhodes and Bob Britzke are collecting at this site, March 2006. World wide, from Canada to China to New Zealand to England. In many states from Maine to the TVA region to New Mexico to Arkansas to the NW New location in Maryland (18): Someone who fishes the Gunpowder is likely to fish the Savage or Big Hunting Creek," Cosden said. "That's been the pattern. The better trout streams is where it's showing up."

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High biomasses found in the tailrace areas and streams below impoundments Important predictor variables of D. geminata abundance included dam presence, water clarity and total phosphorus concentration. When data from dam sites were analyzed, a multiple regression model using mean discharge and pH as independent predictors explained 73% of the variation in D. geminata cell density. Analysis of 3 years of data from one study river (Red Deer River) revealed consistently higher D. geminata cell densities at the dam site compared to the upstream reference. ( 4) Even after flooding the tailrace area within a week biomass of Didymo returned to pre-flood amounts (5) Presence in an Alaskan lake (Lake Naknek) from sediment record (1218-2003) (11) indicating that this organism is not new to North America

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The stalks provide additional substrate for epiphytic diatoms such as Eunotia seen here. The cells are a source of food for invertebrates such as scud, as seen in a previous slide. During the day the cells provide an additional source of oxygen to the water through photosynthesis.

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The damage caused by Didymo is largely from the stalks produced by each cell of the diatom colony which form large mats on streambeds, decreasing clarity and oxygen availability (especially at night). In some areas mats 20cm thick have been reported. (6) When Didymo is absent or in low numbers, diversity of invertebrates is increased.(6) Significant changes in the kinds of invertebrates were found in an excellent study by EcoAnalysts Inc. (12) in examining the effects of Didymo in the Kootenai River, Montana/Idaho EPTs declined (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)), mats were a haven for midges and worms (12) Another study on the negative effects of Didymo was undertaken by Erica Shelby of the Akansas Departent od Environmental Quality (26). She found decreases in the biodiversity of invertebrates associated with populations of Didymo. In New Zealand D. geminata has been correlated to increases of invertebrates that are indicators of poor stream health. (7) Canals used for irrigation and aquifers in California are scraped of Didymo. It also clogs grates in the water supply canal. (2) The stalks create a very unsightly looking benthos on the stream and on the shore where they dry resembling toilet paper.

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Models: One approach is to develop models that may predict the distribution of Didymo based on a sorting of habitats by air temperature, base water flow, precipitation seasonality, and other parameters. The former two seem to be able to account for much of the variance (10) Phosphorus: In an attempt to manage around an infestation of Didymosphenia geminata South Dakota GFP is starting a nutrient-enrichment project this spring that involves artificially increasing total phosphorus in a 3- kilometer section of Rapid Creek immediately below Pactola Dam. The goals of this project are to stimulate productivity, both primary and aquatic insect, and to ultimately increase brown trout growth and survival. (8) Didymo may be able tolerate low or limiting P since it can produce phosphatases as mentioned earlier. Another study on phosphorus uptake in a low concentration by Didymo implicates the enhancement of P uptake by the presence of iron (15) Copper: In New Zealand, a copper compound Gemex@ is being used to control the growth of Didymo. Final field trial results show positive effects of reducing growth of Didymo in applications in New Zealand. (13) Mucinex: Another new approach has been tried in 2009. It involves the application of mucinex, an off the counter mucous loosener. (15) (16)

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DNA testing: One of the latest techniques to assess the presence, low density, and then aggressive public awareness (to follow) and other techniques is a DNA screen (19) Regulating stream flow: The findings suggest that controlled flow releases from reservoirs during the summer could be used to limit the impact of this nuisance species in streams in the Colorado Front Range. Flows below Barker Reservoir near Nederland that are above 200 cubic feet per second similar to those experienced last year once the reservoir started to spill in late June appear to be sufficient to control the didymo… (20) Scouring: Our results suggest that bed movement may be a dominant scouring mechanism that acts to control the growth and distribution of D. geminata. (5) Cleaning after fishing: There have been a number of resources published that focus on clean up. One of the most thorough is: http://www.westdenvertu.org/snails.htm#cleaning (21)http://www.westdenvertu.org/snails.htm#cleaning A well recommended chemical cleanup is best described as follows: I recommend Uncle Jacks Didymo Cleaner to ensure a 100% clean kill of all didymo cells. (22) It is a formulation of benzalkonium chloride (24)Uncle Jacks Didymo Cleaner Uncle Jacks Didymo Cleaner: This is the reference to the cleaner and source of purchase (23). It was tested by NIWA (National Institute of Water and Atmospheric Research, New Zealand. Public awareness: While not an algicide, nutrient enhancement, nor flow control, many states have developed awareness programs through website, posters, and talks such as this to create a public awareness tuned to the prevention of spreading Didymo from one habitat to another. One of the main culprits in this spread is the felt sole of waders. Examples of posters are as follows:

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http://www.anr.state.vt.us/dec//waterq/lakes/docs/ ans/lp_dididguide.pdf Disinfect your boat, trailer, boots & other gear before entering a new body of water Remember -- you cant see individual didymo cells - so thoroughly disinfect all of your equipment Photo - Tim Daley, PA DEP CHECK -- Before you leave a river, stream, or lake, check items and leave debris at site. If you find any later, treat and put in trash. Do not wash down drains. CLEAN -- There are several ways to kill didymo. Choose the most practical treatment for your situation which will not adversely affect your gear. http://www.fish.state.pa.us/water/habitat/ans /didymo/faq_didymo.htm

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In a study of trout in Rapid Creek, South Dakota, the brown trout were stuck with 1 yr or less age fish, with no second year and very few adults since Didymo was first reported in 2002. This stream was one of the top two brown trout fisheries in the state in 1990s….This impact appears to be due to Didymo altering the aquatic insect community and thus impacting the food source for the trout. (8) The relative weight of brown trout below Bull Shoals dam in November 2006 was the lowest that has ever been recorded. Relative weight for both brown and rainbow trout have been falling in Bull Shoals tailwater since 2004, which coincides with the appearance of Didymo. This decrease in relative weight has been documented in other trout waters around the world where Didymo has occurred. (14) We need to be: 1. Surveying likely locations of Didymo 2. Utilizing posters and other information regarding the hazards of not cleaning fishing equipment 3. Spreading the word of the potential impact of a Didymo bloom on the fisheries